Control post mounting for cam ring operated thread chasers



E. P. HALLIGAN CONTROL POST MOUNTING FOR CAM RING OPERATED THREAD CHASERS Oct. 11, 1955 2 Sheets-Sheet 1 Filed Nov. 22, 1952 FIE. 1

Oct. 11, 1955 E. P. HALLIGAN 2,719,983

CONTROL POST MOUNTING FOR CAM RING OPERATED THREAD CHASERS Filed Nov. 22, 1952 2 Sheets-Sheet 2 FIE- 31 Z nited States Patent ()filice 2,719,988 Patented Oct. 11, 1955 CONTROL POST MOUNTING FOR CAM RING OPERATED THREAD CHASERS Eugene P. Halligan, Chicago, 11]., assignor to Nye Tool Company, a corporation of Illinois Application November 22, 1952, Serial No. 322,044

Claims. (Cl. Ill-120.5)

This invention relates to an improved thread cutter of the receding type which is provided with automatic means for stopping the feed of the cutter and retracting the chasers at a predetermined point; and in particular it relates to such a device in which means are provided for manually terminating the cut and retracting the chasers at any time duringthe cutting operation.

The automatic mechanism for terminating the thread cutting operation and retracting the chasers is disclosed and claimed in my copending application Serial No. 139,349, filed January 19, 1950, issued March 3, 1953, as Patent No. 2,629,886. Accordingly this mechanism will be described only insofar as is necessary to an understanding of the improvement here disclosed and claimed.

The principal object of this invention is to provide a simple mechanism by which the thread cutting operation may be terminated at the will of the operator at any time prior to the normal automatic termination of the cut.

A further object is to provide such a mechanism which may be readily incorporated into the basic structure disclosed and claimed in my aforesaid copending application without major modification of any component part thereof.

The invention is illustrated in a preferred embodiment in the accompanying drawings in which:

Fig. 1 is a side elevation of a thread cutter embodying the invention with the control post for terminating the cut in its normal position;

Fig. 2 is a fragmentary elevational view showing the control post in the position which it assumes upon manual termination of a cutting operation;

Fig. 3 is a section taken as indicated along the line 3-3 of Fig. 1 with the control post in its normal position;

Fig. 4 is a fragmentary sectional view like Fig. 3 showing the control post in the position of Fig. 2;

Figs. 5 and 6 are elevational views of the two sides of the control post;

Fig. 7 is an elevational View, partially in section, of the mounting pin for the control post; and

Fig. 8 is an enlarged sectional view taken as indicated along the line 8-8 of Fig. 7.

Referring to the drawings in greater detail, a work holder 9 is provided with clamps 10 by means of which it may be clamped to a pipe P which is held in the head stock of a lathe. As seen in Fig. 3 a cutter head, indicated generally at 11, has a barrel portion 12 provided with a thread 13 to engage an internal thread 14 in the work holder. The cutter 11 includes a recessed flange 15 in which chasers 16 are slidably mounted for radial movement, the positioning of the chasers being controlled by a cam ring 17. The cam ring 17 is spring loaded so that it tends to rotate clockwise so as to retract the chasers 16, and is provided with a spring pressed plunger 18 which may engage either one of two control grooves 19 and 20 in a control post 21. The cam ring 17 may be rotated counter-clockwise against the aforesaid spring loading to engage the spring pressed plunger 18 with either one of the notches 19 or 20, depending upon the mounting of the control-post 21. As best seen in Fig. 3 the control grooves 19 and 20 have inclined surfaces 22 and 23, respectively, at their rear ends to disengage the spring pressed plunger '18 at the rear of said grooves, thus permitting the spring loaded cam ring 17 to rotate clockwise and retract the chasers. At the same time, as described in Patent 2,629,886, a tripping mechanism on the cam control ring 17 disconnects the driving connection between the cutter head 14 and a ratchet drive ring 24 which surrounds the flange 15.

As best seen in Figs. 3 and 4 the control post 21 is slidably mounted upon a pin 25 which is secured to a floating ring 26 on the work holder 10. The control post 21 is generally oval in cross-section, and extends forwardly through a complementary aperture in the flange 15 and has a threaded aperture at its forward end to receive an operating knob 27.

As a cutting operation proceeds the thread 13 on the barrel of the cutter body 14 feeds the cutter body rearwardly with respect to the pipe P, and the spring pressed plunger 18 moves toward the rear of the control groove with which it is engaged. The operator may terminate the cutting operation at will by grasping the operating knob 27 on the control post 21 and pulling it forwardly to the position shown in Figs. 2 and 4. This disengages the spring pressed plunger 18 from the control groove, permitting the spring loaded cam ring 17 to rotate clockwise to retract the chasers and terminate the "cut.

Referring more particularly to the construction of the control post 21 and the mounting pin 25 therefor, and referring first to Figs. 7 and 8, the pin 25 adjacent its forward end is provided with a radial recess 28 which contains a compression spring 29 and a ball 30, the upper margin 31 of the recess 28 being upset to retain the spring and ball within the recess. As best seen in Figs. 3 and 4, the control post 21 has an axial bore 32 to receive the pin 25, and said axial bore has a small depression 33 which is positioned to receive the spring pressed ball 30 when the control post is in the normal position shown in Figs. 1 and 3 with its base abutting the floating ring 26. The control post 21 is also provided with a stop pin 34 which projects from one of its sides so as to engage the cutter head 11 in order to prevent the post from being entirely withdrawn from the mechanism. As shown in Figs. 1 and 2 the stop pin 34 is preferably a flat headed machine screw which is screwed into a threaded aperture 35 in the control post so that the control post may be readily removed and rotated on the pin 25 in order to present either of the grooves 19 or 20 to the spring pressed plunger 18.

Due to dimensional limitations in the automatic receding thread cutter to which the improved control post 21 is applied, the inclined portions 22 and 23 at the rear of the control grooves 19 and 20, respectively, rise to the surface level of the post in two steps, leaving low shoulders indicated as 36 and 37. This so that a large pin 25 may be used without having the material of the post 21 too thin over the end of the bore 32 of the control post. As shown in Figs. 5 and 6, the control groove 19 is parallel to the longitudinal axis of the control post 21 while the groove 20 is diagonal. The post 21 may be removed from the machine and rotated 180 on the pin 25 in order to place either the control groove 19 or the control groove 20 into position to be engaged by the spring pressed plunger 18. The diagonal groove 20 in the control post 21 is so disposed as to turn the cam plate 17 slightly clockwise during a cutting operation, thus gradually receding the chasers 16 to provide a tapered cut. On the other hand the straight axial groove 19 produces a straight cut.

The foregoing detailed description is given for clearness of understanding only and no unnecessary limitations are to be understood therefrom, as some modifications will be obvious to those skilled in the art.

I claim:

1. In a thread cutter of the receding type: a work holder; a cutter head making screw engagement with the work holder; a plurality of radially movable chasers in said cutter head; a cam ring on the cutter head engaging said chasers, said ring being spring loaded toward a position to retract the chasers; a spring pressed control plunger on the cam ring; a floating ring on the work holder; forwardly extending mounting means on said floating ring; and a control post on the mounting means which has a generally longitudinal groove adapted to receive said spring pressed plunger to position the cam ring with said chasers in cutting position, said groove having an inclined surface to disengage the plunger at the rear of the groove, and said control post being mounted for sliding movement only on said mounting means and slidably engaging the cutter head, whereby the control post may be manually moved forward on the mounting means to disengage said plunger from said groove at any time during a cutting operation.

2. The device of claim 1 in which the mounting means is provided with a spring pressed ball which engages a recess in the control post to latch the control post with its base against the floating ring.

3. The device of claim 1 in which the control post is provided with a stop pin to limit forward movement of the post with respect to the cutter head.

4. The device of claim 1 in which the mounting means comprises a pin which extends into a longitudinal bore in the base of the control post.

5. In a thread cutter of the receding type: a work holder; a cutter head making screw engagement with the work holder; a plurality of radially movable chasers in said cutter head; a cam ring on the cutter head engaging said chasers, said cam ring being spring loaded toward a position to retract the chasers; a spring pressed control plunger on the cam ring; a floating ring on the work holder; a forwardly extending pin on said floating ring; a control post having a longitudinal bore in its base by means of which it is mounted for sliding movement only on said pin, said post having a generally longitudinal groove adapted to receive said spring pressed plunger to position the control means with said chasers in cutting position, said groove having an inclined surface to disengage the plunger at the rear of the groove, the sliding mounting of said post on said pin permitting manual movement of the post so as to disengage said plunger from said groove at any time during the cutting operation; a removable stop pin on the control post to limit forward sliding movement of the post with respect to the cutter head; and a spring pressed ball in the mounting pin which frictionally engages the bore of the control post.

References Cited in the file of this patent UNITED STATES PATENTS 1,150,449 Oster Aug. 17, 1915 

